advent-of-code/2021/d09/ex1/ex1.py

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2021-12-09 12:57:23 +01:00
#!/usr/bin/env python
import sys
from typing import Iterator, List, Tuple
HeightMap = List[List[int]]
Point = Tuple[int, int]
def solve(input: List[str]) -> int:
height_map = [[int(c) for c in line] for line in input]
def neighbours_of(point: Point) -> Iterator[Point]:
for dx, dy in (-1, 0), (1, 0), (0, -1), (0, 1):
x, y = point[0] + dx, point[1] + dy
if x < 0 or x >= len(height_map):
continue
if y < 0 or y >= len(height_map[0]):
continue
yield x, y
def is_low_point(point: Point) -> bool:
for neighbour in neighbours_of(point):
if height_map[neighbour[0]][neighbour[1]] <= height_map[point[0]][point[1]]:
return False
return True
def risk_level(point: Point) -> int:
return 1 + height_map[point[0]][point[1]]
points = [(x, y) for x in range(len(height_map)) for y in range(len(height_map[0]))]
return sum(risk_level(p) for p in points if is_low_point(p))
def main() -> None:
input = [line.strip() for line in sys.stdin.readlines()]
print(solve(input))
if __name__ == "__main__":
main()